1992 Volume 58 Issue 1 Pages 52-57
Serological specificity of Agrobacterium tumefaciens biovar 3 was tested by means of agglutination and Ouchterlony double diffusion tests, using rabbit antisera prepared by injecting heat-treated (100°C, 1hr) cell suspensions of 4 Japanese strains of G-Ag-19, 26, 27 and 60, and strain NCPPB 2562, a representative strain for biovar 3 isolated in Greece. In the agglutination test, 39 strains of biovar 3 except strain G-Ag-19 were separated into 4 distinct groups (A-D) according to the titers against 5 antisera. The same group-specific reactions were observed in the Ouchterlony double diffusion test as those in the agglutination test. Each of the biovar 3 strains except strain G-Ag-19 formed several group-specific precipitin bands only in combination with the antiserum prepared against the member of the same group. These results suggest that the biovar 3 strains used are serologically heterogeneous and can be separated into 4 serogroups (A-D), which differ from one another in the reactivity of somatic antigens (heat-stable antigens).